AST guarantor addendum

Hi Guys, I am currently doing a remortgage on a property and the mortgage company are stating that the AST agreement contains adequate provisions to protect the mortgage lender under Ground II Schedule II of the Housing Act 1988 which it currently doesn't. I can either issue a new AST or copy of a notice to the tenants that the property is subject to a mortgage which then needs to be signed by the tenant. Options are to send RLA AST but it doesnt contain a guarantor section for the rent which I require or send a notice but there isnt a notice example on the website. Please advise